Protective and performance enhancing helmet visors, goggles, and other such eye-shielding devices often provide protection for a wearer's eyes while maintaining or enhancing optical functionality for the wearer, for example, by magnifying, clarifying, darkening, tinting, or lightening (“bleaching”) light transmission through the device. In many applications, such as motorcycle helmets, the eye-shielding device such as a visor is configured to match an opening in the helmet for the visor. In particular, the visor and helmet are designed to allow the user to seamlessly pivot the visor up or down. To avoid water penetration between the visor and helmet, the helmet is typically equipped with an elastic gasket which presses against the visor to create a tight seal. To enhance the capability of an eye-shielding device in a variety of conditions, including, for example, fog, condensation, sun glare, or darkness, an enhancing secondary lens (insert) can be used.
While the insert lens may be integrated into an eye-shielding device, in some instances, the insert may be provided as a separate attachment for assembly with or installation on an existing eye-shielding device, for example, for after-market or end user installation.
Typically, an optical insert is configured to fit various sizes and shapes of helmet visors. However, addition or presence of an insert presents several limitations. First, if a flat (non-curved or two-dimensional) optical insert is used, it may not fit a double or multiple curved viewing lens of an eye-shielding device, thus limiting the use of such an optical insert. Second, an insert will create a thickness variation which can significantly hinder the operation of the helmet gasket. In other words, if the insert is large, it can interfere with the sealing properties between the visor and the helmet gasket. On the other hand, if it is smaller than the visor, it may interfere with seamless movement of the visor. For example, the insert may catch the gasket as the user tries to pivot the visor up above the opening. To avoid this, the insert must be sized such that it can fit within the clearance created between the gasket and the visor as the visor is pivoted up. However, this sizing limitation can result in light leakage between the visor insert and the gasket, which can be highly undesirable. This issue has not been addressed with current inserts. Current inserts use either foam or a mechanical clip to hold the insert in place. And to avoid the interference with the gasket, the insert is typically much smaller than the visor.
Thus, it is desirable to have an attachment mechanism that can allow attachment of an optical insert without the limitation associated with the curvature of the visor or the gasket of the helmet, or both.